不平衡电网电压下三相PWM整流器控制策略的研究

在不平衡电网电压下三相电压型PWM整流器的优越性能受到了很大的影响,其原因是由于直流电压产生了奇次谐波以及交流的电流产生了偶次谐波。三相PWM整流器直流侧电压的二次谐波以及在交流侧电流所产生的负序分量都将对整流器负载性能产生影响,同时还将影响直流侧电容寿命。文章提出一种新型不平衡观测器及其控制策略可有效地对不平衡电压进行补偿。通过此控制策略可同时抑制直流侧电压的2次谐波以及减小网侧电流的不平衡度。分析及仿真结果证明了此控制策略的有效性。

A New Control Method for PWM Voltage-Source Converters under Unbalanced Input Voltage Condition

The advanced features of three-phase PWM voltage-source converter are not necessarily achieved under unbalanced input voltage conditions due to the generation of even-order harmonics at DC output and the odd-order harmonics in input currents. Both the 2^nd harmonic voltage component onto the DC link and the negative sequence part of the input currents can disturb the performance of the attached inverter load and reduce the DC link capacitor service life. This paper presents a kind of new observer-based unbalance estimation and control method that compensates source voltage unbalances. The 2^nd harmonics were eliminated and the unbalanced input currents were compensated by this new control method respectively. The presented method also compensates the detrimental impact of delay effects and reduces the PWM switching frequency. Analytical and simulation results are presented to illustrate the effectiveness of the new observer-based control method.